1. Field
The present invention generally relates to an endoscope optical system and more particularly to a system tube of an endoscope optical system and a process for retaining cylindrical elements.
2. Prior Art
An endoscope optical system has an image guide which transfers the image from a distally disposed objective to a proximally disposed viewing device, e.g., an ocular or a video camera. In designs of this class, the image guide is provided with lenses which are packed behind each other in a system tube, optionally with spacing tubes in between, and guided into the optically correct position by it (the system tube). The system tube usually consists of metal.
In this process it is necessary to make sure that the lenses are firmly retained in the system tube so that their position cannot change in case of shaking, which would lead to a disturbing jumping of the viewing direction.
In the case of system tubes of this type, tongues are cut out from the wall of the system tube and deformed nonelastically, permitting the reliable and solid support of the cylindrical elements of the image guide, thus the lenses and optionally also the spacers.
DE 10 2006 041 920 A1 shows a system tube of this type in which the tongues are deformed nonelastically toward the inside. This leads to a constriction of the free cross-section in the area of the tongues, by means of which cylindrical elements disposed in the system tube are reliably clamped or can be guided with low play. Securing of the image guide against rattling of its elements with resulting jumps in the image direction is achieved reliably. However, this known design also has considerable drawbacks. During the insertion of the elements of the image guide into the system tube, clamping forces must be overcome. This interferes with the fine adjustment of the elements. An additional considerable drawback occurs during disassembly, thus when the cylindrical elements of the image guide must be removed again from the system tube. They must then be slid with force from the area of the clamping tongues, which can lead to problems, e.g., to damage.
Patent DE 197 50 685 A1 shows a system tube of an endoscope optical system, wherein openings are provided in the wall of the system tube through which adhesive is introduced in the form of adhesive dots to retain the lenses disposed in the system tube.
DE 197 32 991 A1 shows a system tube in the wall of which beads are disposed, wherein the system tube is deformed toward the inside by these beads and thus lies adjacent to cylindrical elements disposed in the system tube.
The goal of the present invention consists of simplifying the assembly and disassembly of the elements of the image guide in a system tube of the relevant class.